1. Field of the Invention
This invention relates to a sound absorber polymer product containing large amounts of a sound absorbing material bound together by a polymer.
2. Description of the Prior Art
Sound barrier materials have been made by incorporating sound deadening particles into polymer binders. However, the loading levels have been relatively low.
In U.S. Pat. No. 4,110,510 to Oliveira, the sound barrier material comprises a polyvinyl chloride impregnated mesh sheet having a coating of a chlorinated polyethylene containing barium sulfate. This coated sheet is laminated to two sides of an intermediate foam layer. The maximum loading of the barium sulfate in the chlorinated polyethylene binder is a weight ratio of 2:1 so that there are only two parts of barium sulfate to one part of resin binder.
In U.S. Pat. No. 4,010,818 to Westley, the flexible noise barrier is in the form of a mass building coat adhered to a non-woven substrate. The mass building coat consists of neoprene and it has dispersed therein particles of iron sulfide, iron oxide, barium sulfate or barium oxide. In the recipe given the weight of barium sulfate in the neoprene is only equal to the weight of the neoprene. The preferred concentration of particles is 45-55% with the maximum contemplated, based on the total weight, being 70%.
In U.S. Pat. No. 4,191,798 to Schumacher et al, the sound-deadening sheeting is a highly filled thermoplastic composition. It contains 5-50% by weight of an ethylene interpolymer, about 2-15% by weight of processing oil and about 50-90% by weight of filler which can be either calcium carbonate or barium sulfate. It requires the special combination of resins such as vinyl acetate and an ethylene copolymer in addition to the processing oil.
As to hydrogel binders, U.S. Pat. No. 4,246,146 to Wood et al discloses a generic class of elastomeric polyurethane hydrogel compositions which includes the preferred materials of this invention. However, the compositions of the Wood et al patent are mixed with large quantities of fire retardant materials to form a coating which provides a barrier for fire retardant protection. U.S. Pat. 4,241,537 to Wood discloses a plant growth media using polyurethane hydrogel. There is no suggestion in either of these patents of making independent structures for sound deadening purposes.
3. Objects of the Invention
It is an object of this invention to produce a sound deadening composition that can be formed into shapes.
It is a further object to produce a low cost sound deadening composition containing a large amount of an inexpensive (on a per pound basis) sound deadening material and a relatively small amount of the more expensive polymer binder.
It is a further object of this invention to produce a sound deadening composition containing a large quantity of sound absorber particles incorporated in a small amount of a polymer binder, which composition can be formed into desired shapes.
It is a further object of this invention to provide a method to incorporate a large quantity of particles of a sound deadening material into a polymer binder for fabricating into desired shapes.
It is a further object to produce a flexible sound deadening composition having a weight ratio of barium sulfate to polymer binder of greater than 10:1.
These and further objects will become apparent as the description of the invention proceeds.